McLaren expects F1 rival Williams' form to fluctuate during season

The Williams Formula 1 team's upsurge in form over the past two races should not be taken as a sign it will be that competitive for the rest of the season, according to rival McLaren.

Williams overtook McLaren for fifth place in the constructors' championship by finishing third and fourth in the Austrian Grand Prix, and could have won the previous race in Canada following Mercedes' troubles but for a botched pitstop for Felipe Massa.

McLaren has been less competitive over the past two events than its fellow Mercedes customer team, and could only score a best finish of seventh in Austria despite feeling that a major aerodynamic upgrade of the MP4-29 was step in the right direction.

McLaren racing director Eric Boullier praised the job done by Williams with is FW36, but said form would continue to fluctuate depending on the circuit.

"It's interesting because it shows we have a little bit of a strange pecking order in some races, just because of the [track] layout," Boullier said, when asked whether Williams' form in Austria provided hope that Mercedes could be challenged further this season.

"Williams has built a good car - they have some weaknesses but a lot of strengths on some track layouts.

"On a twisty track like Monaco they were not in good form, but on a track with more chicanes and long straightlines - like Canada or Austria - you could see they were on good form.

"This year is very dictated by the power unit, the driveability of the car, and how you deploy your energy - and I think this is why you have this change in the classification across different track layouts."